Magnetic properties of LaNiO3 films and Josephson characteristics of Y1Ba2Cu3O7−y/LaNiO3/Au/Ag/Pb junctions

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Abstract
A conductive perovskite oxide, LaNiO3, has been examined for the application to the normal layer for superconductor‐normal metal‐superconductor junctions for the first time. LaNiO3 films showed resistivity as low as 1.5×10−4 Ω cm. Pauli paramagnetism dominated in the film. The susceptibility measured was 0.9×10−6 emu/Oe g. Boundaries between the Y1Ba2Cu3O7−y and LaNiO3 layers were found to be abrupt in a Y1Ba2Cu3O7−y/LaNiO3 multilayer by transmission electron microscopy (TEM) observation. The coherence length in LaNiO3 was estimated to be 30–70 Å from characteristics of the Y1Ba2Cu3O7−y/LaNiO3/Au/Ag/Pb junctions. The value was comparable to the dirty limit coherence length of (ℏD/2πkBT)1/2 of the conventional theory (D; the diffusion constant in LaNiO3).